update pip version in Readme to 1.4.1

test=develop

README.md

@@ -26,9 +26,9 @@ pip install paddlepaddle
 # Linux GPU cuda9cudnn7
 pip install paddlepaddle-gpu
 # Linux GPU cuda8cudnn7
-pip install paddlepaddle-gpu==1.4.0.post87
+pip install paddlepaddle-gpu==1.4.1.post87
 # Linux GPU cuda8cudnn5
-pip install paddlepaddle-gpu==1.4.0.post85
+pip install paddlepaddle-gpu==1.4.1.post85
 
 # For installation on other platform, refer to http://paddlepaddle.org/
 ```